1/* 2 * include/asm-xtensa/uaccess.h 3 * 4 * User space memory access functions 5 * 6 * These routines provide basic accessing functions to the user memory 7 * space for the kernel. This header file provides functions such as: 8 * 9 * This file is subject to the terms and conditions of the GNU General Public 10 * License. See the file "COPYING" in the main directory of this archive 11 * for more details. 12 * 13 * Copyright (C) 2001 - 2005 Tensilica Inc. 14 */ 15 16#ifndef _XTENSA_UACCESS_H 17#define _XTENSA_UACCESS_H 18 19#include <linux/prefetch.h> 20#include <asm/types.h> 21#include <asm/extable.h> 22#include <asm-generic/access_ok.h> 23 24/* 25 * These are the main single-value transfer routines. They 26 * automatically use the right size if we just have the right pointer 27 * type. 28 * 29 * This gets kind of ugly. We want to return _two_ values in 30 * "get_user()" and yet we don't want to do any pointers, because that 31 * is too much of a performance impact. Thus we have a few rather ugly 32 * macros here, and hide all the uglyness from the user. 33 * 34 * Careful to not 35 * (a) re-use the arguments for side effects (sizeof is ok) 36 * (b) require any knowledge of processes at this stage 37 */ 38#define put_user(x, ptr) __put_user_check((x), (ptr), sizeof(*(ptr))) 39#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr))) 40 41/* 42 * The "__xxx" versions of the user access functions are versions that 43 * do not verify the address space, that must have been done previously 44 * with a separate "access_ok()" call (this is used when we do multiple 45 * accesses to the same area of user memory). 46 */ 47#define __put_user(x, ptr) __put_user_nocheck((x), (ptr), sizeof(*(ptr))) 48#define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr))) 49 50 51extern long __put_user_bad(void); 52 53#define __put_user_nocheck(x, ptr, size) \ 54({ \ 55 long __pu_err; \ 56 __put_user_size((x), (ptr), (size), __pu_err); \ 57 __pu_err; \ 58}) 59 60#define __put_user_check(x, ptr, size) \ 61({ \ 62 long __pu_err = -EFAULT; \ 63 __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ 64 if (access_ok(__pu_addr, size)) \ 65 __put_user_size((x), __pu_addr, (size), __pu_err); \ 66 __pu_err; \ 67}) 68 69#define __put_user_size(x, ptr, size, retval) \ 70do { \ 71 int __cb; \ 72 retval = 0; \ 73 switch (size) { \ 74 case 1: __put_user_asm(x, ptr, retval, 1, "s8i", __cb); break; \ 75 case 2: __put_user_asm(x, ptr, retval, 2, "s16i", __cb); break; \ 76 case 4: __put_user_asm(x, ptr, retval, 4, "s32i", __cb); break; \ 77 case 8: { \ 78 __typeof__(*ptr) __v64 = x; \ 79 retval = __copy_to_user(ptr, &__v64, 8) ? -EFAULT : 0; \ 80 break; \ 81 } \ 82 default: __put_user_bad(); \ 83 } \ 84} while (0) 85 86 87/* 88 * Consider a case of a user single load/store would cause both an 89 * unaligned exception and an MMU-related exception (unaligned 90 * exceptions happen first): 91 * 92 * User code passes a bad variable ptr to a system call. 93 * Kernel tries to access the variable. 94 * Unaligned exception occurs. 95 * Unaligned exception handler tries to make aligned accesses. 96 * Double exception occurs for MMU-related cause (e.g., page not mapped). 97 * do_page_fault() thinks the fault address belongs to the kernel, not the 98 * user, and panics. 99 * 100 * The kernel currently prohibits user unaligned accesses. We use the 101 * __check_align_* macros to check for unaligned addresses before 102 * accessing user space so we don't crash the kernel. Both 103 * __put_user_asm and __get_user_asm use these alignment macros, so 104 * macro-specific labels such as 0f, 1f, %0, %2, and %3 must stay in 105 * sync. 106 */ 107 108#define __check_align_1 "" 109 110#define __check_align_2 \ 111 " _bbci.l %[mem] * 0, 1f \n" \ 112 " movi %[err], %[efault] \n" \ 113 " _j 2f \n" 114 115#define __check_align_4 \ 116 " _bbsi.l %[mem] * 0, 0f \n" \ 117 " _bbci.l %[mem] * 0 + 1, 1f \n" \ 118 "0: movi %[err], %[efault] \n" \ 119 " _j 2f \n" 120 121 122/* 123 * We don't tell gcc that we are accessing memory, but this is OK 124 * because we do not write to any memory gcc knows about, so there 125 * are no aliasing issues. 126 * 127 * WARNING: If you modify this macro at all, verify that the 128 * __check_align_* macros still work. 129 */ 130#define __put_user_asm(x_, addr_, err_, align, insn, cb)\ 131__asm__ __volatile__( \ 132 __check_align_##align \ 133 "1: "insn" %[x], %[mem] \n" \ 134 "2: \n" \ 135 " .section .fixup,\"ax\" \n" \ 136 " .align 4 \n" \ 137 " .literal_position \n" \ 138 "5: \n" \ 139 " movi %[tmp], 2b \n" \ 140 " movi %[err], %[efault] \n" \ 141 " jx %[tmp] \n" \ 142 " .previous \n" \ 143 " .section __ex_table,\"a\" \n" \ 144 " .long 1b, 5b \n" \ 145 " .previous" \ 146 :[err] "+r"(err_), [tmp] "=r"(cb), [mem] "=m"(*(addr_)) \ 147 :[x] "r"(x_), [efault] "i"(-EFAULT)) 148 149#define __get_user_nocheck(x, ptr, size) \ 150({ \ 151 long __gu_err; \ 152 __get_user_size((x), (ptr), (size), __gu_err); \ 153 __gu_err; \ 154}) 155 156#define __get_user_check(x, ptr, size) \ 157({ \ 158 long __gu_err = -EFAULT; \ 159 const __typeof__(*(ptr)) __user *__gu_addr = (ptr); \ 160 if (access_ok(__gu_addr, size)) \ 161 __get_user_size((x), __gu_addr, (size), __gu_err); \ 162 else \ 163 (x) = (__typeof__(*(ptr)))0; \ 164 __gu_err; \ 165}) 166 167extern long __get_user_bad(void); 168 169#define __get_user_size(x, ptr, size, retval) \ 170do { \ 171 int __cb; \ 172 retval = 0; \ 173 switch (size) { \ 174 case 1: __get_user_asm(x, ptr, retval, 1, "l8ui", __cb); break;\ 175 case 2: __get_user_asm(x, ptr, retval, 2, "l16ui", __cb); break;\ 176 case 4: __get_user_asm(x, ptr, retval, 4, "l32i", __cb); break;\ 177 case 8: { \ 178 u64 __x; \ 179 if (unlikely(__copy_from_user(&__x, ptr, 8))) { \ 180 retval = -EFAULT; \ 181 (x) = (__typeof__(*(ptr)))0; \ 182 } else { \ 183 (x) = *(__force __typeof__(*(ptr)) *)&__x; \ 184 } \ 185 break; \ 186 } \ 187 default: \ 188 (x) = (__typeof__(*(ptr)))0; \ 189 __get_user_bad(); \ 190 } \ 191} while (0) 192 193 194/* 195 * WARNING: If you modify this macro at all, verify that the 196 * __check_align_* macros still work. 197 */ 198#define __get_user_asm(x_, addr_, err_, align, insn, cb) \ 199do { \ 200 u32 __x = 0; \ 201 __asm__ __volatile__( \ 202 __check_align_##align \ 203 "1: "insn" %[x], %[mem] \n" \ 204 "2: \n" \ 205 " .section .fixup,\"ax\" \n" \ 206 " .align 4 \n" \ 207 " .literal_position \n" \ 208 "5: \n" \ 209 " movi %[tmp], 2b \n" \ 210 " movi %[err], %[efault] \n" \ 211 " jx %[tmp] \n" \ 212 " .previous \n" \ 213 " .section __ex_table,\"a\" \n" \ 214 " .long 1b, 5b \n" \ 215 " .previous" \ 216 :[err] "+r"(err_), [tmp] "=r"(cb), [x] "+r"(__x) \ 217 :[mem] "m"(*(addr_)), [efault] "i"(-EFAULT)); \ 218 (x_) = (__force __typeof__(*(addr_)))__x; \ 219} while (0) 220 221 222/* 223 * Copy to/from user space 224 */ 225 226extern unsigned __xtensa_copy_user(void *to, const void *from, unsigned n); 227 228static inline unsigned long 229raw_copy_from_user(void *to, const void __user *from, unsigned long n) 230{ 231 prefetchw(to); 232 return __xtensa_copy_user(to, (__force const void *)from, n); 233} 234static inline unsigned long 235raw_copy_to_user(void __user *to, const void *from, unsigned long n) 236{ 237 prefetch(from); 238 return __xtensa_copy_user((__force void *)to, from, n); 239} 240#define INLINE_COPY_FROM_USER 241#define INLINE_COPY_TO_USER 242 243/* 244 * We need to return the number of bytes not cleared. Our memset() 245 * returns zero if a problem occurs while accessing user-space memory. 246 * In that event, return no memory cleared. Otherwise, zero for 247 * success. 248 */ 249 250static inline unsigned long 251__xtensa_clear_user(void __user *addr, unsigned long size) 252{ 253 if (!__memset((void __force *)addr, 0, size)) 254 return size; 255 return 0; 256} 257 258static inline unsigned long 259clear_user(void __user *addr, unsigned long size) 260{ 261 if (access_ok(addr, size)) 262 return __xtensa_clear_user(addr, size); 263 return size ? -EFAULT : 0; 264} 265 266#define __clear_user __xtensa_clear_user 267 268 269#ifdef CONFIG_ARCH_HAS_STRNCPY_FROM_USER 270extern long __strncpy_user(char *dst, const char __user *src, long count); 271 272static inline long 273strncpy_from_user(char *dst, const char __user *src, long count) 274{ 275 if (access_ok(src, 1)) 276 return __strncpy_user(dst, src, count); 277 return -EFAULT; 278} 279#else 280long strncpy_from_user(char *dst, const char __user *src, long count); 281#endif 282 283/* 284 * Return the size of a string (including the ending 0!) 285 */ 286extern long __strnlen_user(const char __user *str, long len); 287 288static inline long strnlen_user(const char __user *str, long len) 289{ 290 if (!access_ok(str, 1)) 291 return 0; 292 return __strnlen_user(str, len); 293} 294 295#endif /* _XTENSA_UACCESS_H */ 296